The invention pertains to a steering column lock of the type indicated in the introductory clause of Claim 1. In an unmoving vehicle, a locking bar for the steering column is in its locking position, with the result that the steering column cannot be turned. When an unauthorized person tries to tear the rotor out of the steering column lock, an anti-theft device is activated. The anti-theft device consists of a spring-loaded locking pin and a securing element, which cooperates with the pin. When the steering column lock is broken open, the securing element releases the spring-loaded locking pin, which then moves into its extended position and blocks the locking bar. Even though the rotor has been torn out, the unauthorized person cannot move the locking bar into the releasing position. The vehicle is thus theft-proof.
In the known device of this type (EP 0 806 328 A2), the securing element consists of a sheet-metal strip provided with a predetermined break point; one end of the strip acts on the rotor, whereas the other end has a prong, which grips under a shoulder on the locking pin. When the rotor is torn out, the sheet-metal strip breaks in two and thus releases the locking pin. The locking pin travels into a recess in a slider in the housing. The slider is connected to the locking bar and moves the locking bar between the locking position and the releasing position by way of the control cam.
This known anti-theft device is susceptible to malfunctions and is thus unreliable. A significant disadvantage is that the known steering column lock can only be delivered with the rotor already installed. In the case of access authorization means that operate mechanically, the rotor consists, for example, of a lock cylinder, which is coded to work with the key assigned to it. When the known steering column locks are delivered, each individual key must be assigned to the steering column belonging to it and must remain thus assigned until the vehicle is delivered. This is very cumbersome. Similar difficulties arise when a defective lock cylinder must later be replaced, whereupon the anti-theft device must be activated again.
The invention is based on the task of developing a reliable steering column lock of the type indicated in the introductory clause of Claim 1 with an anti-theft device, which lock allows authorized parties to install and remove the rotor, but which, after the rotor has been torn out by an unauthorized person, reliably blocks the steering column. These apparently mutually contradictory goals are accomplished according to the invention by the measures cited in Claim 1, to which the following special meaning attaches:
The problem that the invention solves is how to allow an authorized person to perform easily an action such as installing or removing the rotor while at the same time an unauthorized person is prevented from doing so. Only in the latter case should the anti-theft device be activated to prevent manipulations of the locking bar. To solve this problem, the invention makes use of the difference between these two types of persons, this difference being that only the authorized person will have the correct access authorization means which make it possible for him to move the rotor from the home position in the parked vehicle to the working position required for the operation of the vehicle. For this reason, the invention proposes that the spring-loaded locking pin belonging to the anti-theft device be integrated into the components which rotate concomitantly with the rotor as it moves from one position to another. The invention proposes that the control cam be used as the component to accomplish this purpose, even though it would also be possible to use other components which rotate concomitantly with the turning of the rotor. When an unauthorized position tampers with the steering lock of a parked vehicle and removes the rotor, a spring-loaded element ensures that the locking pin in the control cam is released. Because this locking pin is spring-loaded, it will then be able to move into a locking recess in the housing. This has the effect of preventing the control cam from rotating, and thus no further manipulations such as turning the cam, which could have the effect of moving the locking bar out of its locking position into the releasing position, are possible.
The authorized position, i.e., the person with the correct access authorization means in his possession, however, is able to move the rotor into its working position, e.g., into the xe2x80x9cdrivexe2x80x9d position of an ignition switch, which is combined with the steering column lock. As a result, the locking pin in the control cam arrives in a rotational position in which it is supported against an inside surface of the housing, and this makes it possible for the control cam to be turned later by the rotor, after it has been reinstalled. The invention takes advantage of this property to preassemble the steering column locks to form preliminary units without their rotors and to deliver them in this form. Thus it is possible to produce the components very easily and efficiently without the need to take into account the individual access authorization means. These preliminary rotorless steering column products can be manufactured in large quantities, and then, during the final assembly work on the vehicle, for example, they can be provided with their individual rotors and access authorization means, such as keys.
This preliminary steering column product is assembled so that it is in a special xe2x80x9cdelivery positionxe2x80x9d according to the invention, which position corresponds to the working position of the control cam which can be reached under normal conditions only by the use of the access authorization means. In this position, as already mentioned above, the spring-loaded locking pin is supported against an inside surface of the housing and, after installation of the rotor, allows the control cam to rotate back to its home position. As a result, it is a very simple matter to produce, to transport, to install, and to repair the steering column locks according to the invention. The paired components according to the invention, i.e., the rotor and the access authorization means, are installed into the previously mentioned separate preliminary steering column lock product only at the last moment. It is also possible to replace a defective rotor at a later time without the need to remove the means used to prevent unauthorized persons from breaking the lock. These anti-theft means always remain intact. The authorized person with the access authorization means does not need to worry about the anti-theft device of the lock at all; he or she will not even notice that such a device is present. The anti-theft device acts reliably only against a thief.